line 119 in this file : /usr/local/ispconfig/interface/admin/software_package_list.php
include_once('lib/lang/en_software_package_list.lng');
remplace by
include_once('lib/lang/'.$_SESSION['s']['language'].'_software_package_list.lng');

line 214 in this file : /usr/local/ispconfig/interface/admin/software_update_list.php
include_once('lib/lang/en_software_update_list.lng');
remplace by
include_once('lib/lang/'.$_SESSION['s']['language'].'_software_update_list.lng');